In this artist's conception, an ascent module lifts off from the Martian surface,
carrying samples of soil and rock on a key part of the journey back to Earth.
Fifty years after NASA began grappling with the idea of life beyond our planet, it's in the midst of planning missions to bring potential traces of Martian life back to Earth ... again.
NASA's goal of looking for extraterrestrial life is almost as old as the space agency itself: In 1960, a bioscience advisory committee recommended that NASA should get involved in exobiology as well as space medicine, and in that same year the Jet Propulsion Laboratory was authorized to start figuring out what kind of spacecraft would be needed to search for life on Mars.
In the 1970s, NASA's Viking missions to Mars included experiments that scientists thought would reveal whether life exists there - but the results were inconclusive at best. NASA researchers also found evidence of bacteria-like "nanofossils" in meteorites that were blasted away from the Red Planet and fell to Antarctica. Those findings are still under debate as well.
A dozen years ago, NASA's David McKay - one of the researchers behind the nanofossil find - told me that the verdict on Martian life might have to wait until fresh samples are brought back to Earth for detailed study. "I think that'll be really definitive," he said at the time.
When I spoke with McKay back then about bringing samples back from Mars, he thought the job would be done by 2007. In fact, NASA's original exobiology plan called for 100 missions to be flown to Mars by this time. But reality has fallen far short of the plan. NASA's proposals for a Mars sample return have been stymied repeatedly, due to cost and logistical considerations.
Over the past couple of years, scientists have been closing in on another sample return concept - and the radical shift in NASA's space vision, announced just this month, could conceivably bring the plan for bringing back Mars life into sharp focus.
Here's the current timeline, as laid out by the Mars Exploration Program Analysis Group, or MEPAG:
- In 2018, a U.S.-European mission would send a sample-gathering rover known as MAX-C to Mars, perhaps in combination with Europe's Exomars rover. MAX-C would drive around and build up a cache of rock and soil samples suitable for sending back.
- In 2022 or so, another rover would descend to the Martian surface, link up with MAX-C and deposit the samples into a rocket-equipped return capsule.
- In the mid- to late 2020s, an orbiter would be launched to Mars. At just the right moment, the return capsule would blast away from its roving launch pad and rendezvous with the orbiter. The orbiter would carry the capsule back toward Earth and fling it into a drop zone for recovery. That part of the operation would work much like the Stardust comet sample return mission.
All this may sound as if it's a distant dream - but Cassie Conley, NASA's planetary protection officer, noted that the plan for dealing with the potential exo-biohazard on Earth should be in place a good 10 years before the samples come back. That suggests that there's only a few years left to settle on key elements of the plan, including a decision on where the samples will be brought.
Sending astronauts to Mars
There's another factor driving the Mars planning process forward, which has to do with NASA's long-range exploration goals. This month's vision switch called for the cancellation of the space agency's back-to-the-moon plan, but at a congressional hearing today, NASA Administrator Charles Bolden said he was aiming instead to send astronauts to Mars ... eventually.
"At this particular time, I can't provide a date certain for the first human mission to Mars," Bolden told the Senate's science and space subcommittee. However, Bolden recently told the Houston Chronicle's editorial board it was his "personal vision" to put NASA on a path toward a human Mars landing sometime in the 2030s.
That's the kind of talk that could energize further robotic exploration of Mars, including two-way trips. "Non-human sample return would feed very directly into the technology for human exploration," Conley told me.
If Bolden's vision holds true, a lot of questions will have to be answered in the next 20 years. Conley said one biggie is how safe astronauts would be on the Red Planet. A report from the National Research Council, titled "Safe on Mars," outlined a whole list of potential nasties ranging from alien microbes to toxic hexavalent chromium. Some of those risks can be assessed only by up-close analysis of Martian samples, Conley said.
Safe on Earth?
Another big question has to do with how safe earthlings would be if and when material is brought back from Mars. That's the reason why Conley serves as planetary protection officer - a job title that sounds as if it came from a science-fiction screenplay.
"When we bring samples back from Mars, somebody's got to protect us from Mars - and we don't trust astrobiologists to do that," said John Rummel, who once held Conley's job and is now the director of East Carolina University's Institute for Coastal Science and Policy. Rummel also heads the planetary protection panel at the International Council for Science's Committee on Space Research, a.k.a. COSPAR.
Rummel, Conley and other experts on astrobiology discussed the past, present and future of exobiology (or astrobiology, which is the preferred term nowadays) in San Diego over the weekend during the annual meeting of the American Association for the Advancement of Science.
When fresh Martian material is brought back - either by astronauts or by special-delivery robots - it'll have to be contained much more tightly than the Apollo moonwalkers were 40 years ago. The way Rummel sees it, our planet was lucky that the moon was most sincerely dead. "If there had been anything alive on the moon at that time, it would be alive here now," he said. (On the flip side, we may have left something alive on the moon.)
NASA's plans call for Martian samples to be handled as if they were top-priority biohazards, in a containment facility equivalent to a Biosafety Level 4 lab. The sample capsule would have to be built to withstand a crash landing (like the unfortunate Genesis crash of 2004).
If sample analysis indeed finds definitive signs of life on Mars, that could revolutionize our perspective on the universe. But it's also possible that no signs will be found - or that scientists will have a hard time deciding what they see is actually "life" or not.
Back in 1960, NASA's exobiologists thought the questions about life beyond Earth would be answered by now. Today it's clear that those questions will still be debated for years to come. NASA's next rover, due for launch in 2011 after a series of troubles, won't address the life-on-Mars question directly - but it will set the stage for the missions to come by studying whether life could have existed on Mars.
"The period of biological exploration ... in fact, is only beginning," Rummel said. "Life begins at 50."
Feel free to chime in with your comments below, and click the links to learn more about life on Mars:
- Life on Mars, or merely static?
- Caves discovered on Mars
- Is Martian life on ice?
- 'Mermaid on Mars' explained
- Was Mars too salty for life?
- Water found (and lost) on Mars
- Life on Mars, continued
It turns out that 1960 was a big year for discoveries: To find out why, check out our roundup of 50 years' worth of science sagas ... celebrate this year's golden anniversary for lasers ... and learn about the past and future of the search for alien signals.
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